Re: xm mem-set causes kernel panic

[Andrew Theurer <habanero@us.ibm.com>]

Krysan, Susan wrote:
> We did run using unstable. We installed sles10 beta11 but we pulled and built xen-unstable changeset 9903 from xensource repository.  We have not tried with PAE hypervisor.  It is not our focus.  How desperately would you need us to try PAE?
>   
I have done this on 32GB x86_64 as well and have pretty much the same 
problem.  I think the problem is that the static memory allocations in 
the kernel for things like mem_map, page_struct etc, are quite large for 
32GB, and do not shrink (or do they?) when balooning to 512 MB.  This 
leaves almost no usable memory when balooning down, and you get OOM.  If 
you know you don't need 32G for dom0, I would try setting dom0_mem to 
something much lower, like 1GB.

-Andrew Theurer
> Thanks,
>
>   
>> Sue Krysan
>> Linux Systems Group
>> Unisys Corporation
>>
>>     
>
>
> -----Original Message-----
> From: Ian Pratt [mailto:m+Ian.Pratt@cl.cam.ac.uk]
> Sent: Wednesday, May 03, 2006 4:19 PM
> To: Krysan, Susan; xen-devel@lists.xensource.com
> Cc: Subrahmanian, Raj; Vessey, Bruce A; Puthiyaparambil, Aravindh; Carb,
> Brian A; ian.pratt@cl.cam.ac.uk
> Subject: RE: [Xen-devel] xm mem-set causes kernel panic
>
>
>   
>> When I boot the ES7000 with 32 GB of RAM, dom0 is allocated 
>> almost all of it.  I issued an xm mem-set 0 512 command to 
>> decrease dom0's memory to 512 MB.  Using xentop, I see the 
>> amount of memory allocated to dom0 slowly decrease.  The 
>> kernel panic occurs when dom0's memory is around 1 GB.  The 
>> serial console output is attached.  Using SLES10 Beta 11 
>> upgraded to xen changeset 9903.
>>     
>
> Can you repro this on -unstable? What about with a PAE hypervisor?
>
> Thanks,
> Ian
>
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